The present invention relates generally to powered tool drivers such as electric or pneumatic power drivers. More particularly, the present invention relates to such drivers having a chuck of the keyless type.
Power tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools. Since the tool shank may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck that is adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore or any other suitable means.
A variety of chuck types have been developed that are actuated by relative rotation between a chuck body and an annular nut. In a typical oblique jawed chuck, for example, a body member includes three passageways disposed approximately 120.degree. apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis forward of the chuck body. Three jaws are constrained by and movable in the passageways to grip a cylindrical tool shank disposed approximately along the chuck's center axis. The nut rotates about the chuck's center and engages threads on the jaws so that rotation of the nut moves the jaws in either direction in the passageways. The body and nut are configured so that rotation of the nut in one direction (the closing direction) with respect to the body forces the jaws into gripping relationship with the tool shank, while rotation in the opposite direction (the opening direction) releases the gripping relationship. Such a chuck may be keyless if it is rotated by hand. Examples of such chucks are disclosed in U.S. Pat. Nos. 5,125,673 and 5,193,824, commonly assigned to the present assignee and the entire disclosure of each of which is incorporated by reference herein. Various configurations of keyless chucks are known in the art and are desirable for a variety of applications.
Keyless chucks actuated by relative rotation between a nut and a chuck body include means to control the rotational position of the nut and the body. For example, a first sleeve may be provided in communication with the nut while a second sleeve, which is independent of the first sleeve, may be attached to the body. Thus, a user may rotate the first sleeve with one hand while gripping the second sleeve with the other hand, thereby holding the body still. Alternatively, in some devices in which only a single sleeve is provided, a user may grip the single sleeve and actuate the tool driver to rotate the spindle, thereby rotating the chuck body with respect to the sleeve. In addition, a mechanism may be located in a driver to lock the spindle of the driver when the driver is not actuated, thus enabling use of a single sleeve chuck.